A Study Evaluating Oxybutynin in Patients With Neurogenic Overactive Bladder Associated With a Neurological Condition: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study Evaluating Oxybutynin in Patients With Neurogenic Overactive Bladder Associated With a Neurological Condition (NCT00224029), a non-randomized phase 4 study. The primary outcome is Average Number of Catheterizations Without Leaking Per Day.

2. Clinical Question

In practical terms, the study was set up to examine daily dry catheterizations in participants receiving oxybutynin through a transdermal system. The outcome description refers to a 3-day urinary diary for the baseline measure. The record does not explain how baseline and follow-up values were compared, or whether the primary question was framed as a change from baseline, a value at follow-up, or another contrast.

Because the study has no control group, its results cannot by themselves distinguish changes during treatment from changes that might have occurred for other reasons. The registry record also does not report the outcome values, a treatment-effect estimate, a confidence interval, or a statistical test for the primary outcome. The clinical question can therefore be described from the study plan, but its numerical answer is not reported in the registry record.

3. Trial Design

This is a Phase 4, multi-center, open-label, dose-titration pilot study. The registry record describes a single-group model, non-randomized allocation and no masking. Enrollment is listed as 24. The intervention is an oxybutynin transdermal system, with doses listed as 3.9 mg/day, 7.8 mg/day, 9.1 mg/day or 11.7 mg/day. Although the title describes dose titration, the sequence, timing and decision rules for changing doses are not reported in the registry record.

The study concerns neurogenic bladder resulting from spinal cord injury, and the listed condition is detrusor hyperreflexia. Its primary measure is the average number of catheterizations without leaking per day, with an 8-week timeframe. Secondary outcomes named in the record include patch adhesion, urodynamic measurements, and urinary leakage and catheterization data. The registry record lists four outcome measures overall, but does not provide the numerical findings for them.

A single-group design can describe what was observed among participants during the study, but it does not include a concurrent untreated or alternative-treatment group for comparison. Non-randomized allocation and open-label conduct also mean that participants and investigators were not masked to the intervention, as the record states. These features matter when interpreting observed changes: without a control group, a change cannot be attributed to the intervention on the basis of a controlled contrast.

The record lists the study as completed, with a start date of 2004-12 and primary completion of 2005-12. It does not report a detailed protocol, a statistical analysis plan, a sample-size justification, or interim analyses. The record lists no analyses. Thus, design features and planned outcome definitions can be described, but the intended inferential procedures and numerical outcome findings are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: washout of previous anticholinergic therapy during the screening period

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The number of participants for analysis is determined by Last Observation Carried Forward (LOCF.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Average Number of Catheterizations Without Leaking Per Day, measured over 8 weeks.

The primary endpoint is the average number of catheterizations without leaking per day, expressed as a number of dry catheterizations per day. It is a count-like daily measure summarized as a mean, so it represents an average frequency rather than the experience on any single catheterization. The record associates the baseline value with a 3-day urinary diary and gives an 8-week timeframe for the endpoint.

Dry catheterizations are relevant to the study’s stated focus on urinary leakage and catheterization. A diary-based measure can capture repeated day-to-day events in a participant’s usual setting, rather than relying on a single recollection. Averaging daily observations can also make a measure easier to compare across participants than describing each diary entry separately. These are general reasons such measures may be used; the registry record does not state the specific rationale for selecting this endpoint.

The measure is described as a mean with standard deviation as its dispersion. A mean describes the central average, while a standard deviation describes how spread out individual observations are around that average. The registry record does not report the mean, standard deviation, number of participants contributing to the primary analysis, or a numerical comparison between baseline and follow-up. It therefore does not establish the size or precision of any observed change.

The record says the analysis population is determined by Last Observation Carried Forward, but does not provide further details about which observations were carried forward or how missing diaries were handled. The endpoint description also does not specify the exact follow-up aggregation procedure. These omissions limit how fully the measure and its analysis can be reconstructed.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the primary measure summarize?

The primary outcome is specified as a mean for a continuous measure: the average number of catheterizations without leaking per day. Although each daily value is a count, the registry record identifies the analysis parameter as a mean and the dispersion measure as a standard deviation. In general, a mean combines observations into an average, while a standard deviation describes the spread of observations around that average. These summaries convey different information: the mean describes the center, and the standard deviation describes variability among observations.

The endpoint description refers to a 3-day urinary diary for the baseline measure and gives an 8-week timeframe. The record does not explain the exact construction of the follow-up summary, how diary days were combined, or the precise contrast between baseline and follow-up. Those details are needed to reproduce the endpoint analysis. The observed mean and standard deviation are also not reported in the registry record.

How would a treatment effect be expressed?

In general, an effect estimate for a repeated measure might describe a change from baseline, or a difference between groups at follow-up. The choice depends on the design and prespecified analysis. This study is listed as single-group, so it has no concurrent control-group contrast. The registry record does not state whether the primary analysis used a change score or another summary, and it does not report an effect estimate. No new contrast can be reconstructed from the information in the record.

A confidence interval is a statistical interval that expresses uncertainty around an estimate under the assumptions of the analysis. A narrower interval indicates greater precision than a wider one, but precision is not the same as freedom from bias. In a single-group study, a precise estimate of change would still not establish how much of that change was caused by treatment. No confidence interval is reported for the primary outcome.

Why does variability matter?

Participants may differ in their diary values, and an average alone does not show how much values vary. The standard deviation is one summary of that spread. If the observations are more variable, an estimate may be less precise for a given amount of data. General methods for count outcomes may also need to account for over-dispersion, which occurs when count variability is greater than a simple model expects. The registry record does not report a model for the primary endpoint or provide enough numerical detail to assess whether over-dispersion was considered.

What can be learned from the registry’s analysis information?

The record lists no analyses and does not report an analysis plan, test statistic, model, adjustment method, or primary-outcome p-value. A p-value, in general, measures how compatible observed data are with a specified null hypothesis under a statistical model. It does not state the probability that a treatment works, and it does not convey the size of an effect. Since no p-value or testing method is reported, statistical significance cannot be assessed from the registry record.

The record describes the primary analysis population as determined by Last Observation Carried Forward. In general, this method substitutes a participant’s last observed value for a later missing value. Its validity depends on assumptions about why values are missing and how outcomes would otherwise have changed. Carrying an earlier observation forward can fail to represent later outcomes if participants’ values change after their last measurement. The record does not report how many values were missing, how many were carried forward, or any sensitivity analysis.

What do the planning illustrations represent?

The planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect set to a stated fraction of the observed effect. Such calculations are hypothetical planning exercises, not observed study outcomes and not observed power. They do not change the fact that the clinical study itself is recorded as a single-group design. The registry record does not report the trial’s own sample-size justification or statistical plan. Without reported primary-outcome estimates or the numerical planning results, those illustrations cannot be interpreted as evidence about the treatment effect.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists four outcome measures, including the primary outcome and secondary outcomes concerning patch adhesion, urodynamic measurements, and urinary leakage and catheterization data. It does not report a multiplicity plan, such as how statistical testing across several outcomes would be handled. When several outcomes or tests are examined, the chance of at least one apparently unusual result can increase. General approaches to multiplicity address that issue, but no particular approach is reported for this study.

The record lists no analyses and does not provide numerical results or p-values for the primary or secondary outcomes. It also does not report whether any outcomes were added, removed, or changed from an earlier protocol. A protocol, prespecified analysis plan, interim-analysis plan, and details of outcome reporting are not reported in the registry record. Therefore, it is not possible to assess whether reported analyses followed a prespecified hierarchy or whether multiplicity was considered.

For missing data, the primary analysis population is described as determined by Last Observation Carried Forward. In general, this method uses a participant’s last observed outcome value in place of a later missing value. The record does not explain the reasons for missing observations, the extent of missingness, or the number of participants included in the primary analysis. It also does not report sensitivity analyses that might show whether conclusions depend on the missing-data approach.

The record does not describe how analysis populations were defined beyond the LOCF statement. It does not say whether all enrolled participants were included in the primary analysis or how departures from the intended treatment were handled. These omissions matter because exclusions and missing-data choices can affect estimates and their precision. Without analysis counts and outcome results, the impact of these choices cannot be evaluated.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry record reports that 24 participants were at risk for serious adverse events and that 0 were reported as affected by serious adverse events. For other adverse events, 24 were at risk and 11 were reported as affected. These are participant counts in the oxybutynin transdermal system group. They do not describe the number of individual events, their duration, severity, or relationship to treatment.

No serious adverse-event terms are listed in the record. Deaths are not reported in the registry record. The absence of listed serious-event terms should be read as a feature of the posted record, not as proof that no other safety information exists. The record does report zero participants affected by serious adverse events, but it does not provide additional details about event definitions, collection procedures, or follow-up completeness.

Safety counts in a single-group study do not provide a comparative estimate against an untreated or alternative-treatment group. The other-adverse-event count also does not indicate how many events each affected participant experienced. These figures describe what the registry reports for the study group; they do not establish comparative risk or determine whether an event was caused by the intervention.

12. What the Result Does, and Does Not, Mean

The registry record documents a completed, open-label, single-group pilot study of oxybutynin transdermal systems in adults with neurogenic bladder associated with spinal cord injury. It identifies the primary outcome as the average number of catheterizations without leaking per day, with an 8-week timeframe, and gives a baseline diary description. It also records the intended dose range and lists secondary outcome topics.

The record does not report the numerical primary-outcome results, an estimate of change, a standard deviation, a confidence interval, or a p-value. No inferential analyses are listed. Consequently, the posted information does not establish how the primary outcome changed, how precisely it was estimated, or whether any change was statistically distinguishable from chance under a specified model.

Even numerical before-and-after results would need careful interpretation because there is no concurrent comparator group. An observed change in a single group cannot isolate the intervention’s effect from other explanations for change over time. The open-label design also means treatment was not masked, as recorded. These design features do not make descriptive observations meaningless, but they limit what those observations can establish about causation.

The adverse-event figures report 0 of 24 participants affected by serious adverse events and 11 of 24 affected by other adverse events. The record does not list serious-event terms, and deaths are not reported in the registry record. These counts are descriptive and do not provide a comparison with another group.

In short, the record specifies a clinical question and provides some design and safety information, but it does not provide the outcome results needed to quantify an efficacy finding. It should not be read as evidence for or against a treatment effect. The outcome’s size, precision, and clinical importance are not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically notable because its primary question concerns a repeated daily measure, while the registry describes a single-group design. A diary-based average can summarize activity across days, but interpretation depends on how the observations are aggregated and compared. The record identifies the baseline diary duration and an 8-week timeframe, yet it does not describe the exact follow-up calculation or report numerical results.

The design illustrates the distinction between measuring change and estimating a comparative treatment effect. A single group can be described over time, but without a concurrent comparator, alternative explanations for change cannot be separated using a controlled contrast. This makes design central to the interpretation, rather than a technical detail that can be resolved by choosing a more elaborate statistical model.

The record also highlights the importance of transparent reporting. It lists an analysis population based on Last Observation Carried Forward, but does not give missing-data counts, analysis numbers, or sensitivity analyses. It names multiple outcomes without reporting a multiplicity approach. No analysis plan or sample-size justification is reported in the registry record. Such information is important for judging how the analysis was specified and how robust results might be to analytic choices.

Finally, the record demonstrates why outcome definitions alone do not answer a clinical question. The primary endpoint is identifiable, and enrollment and safety counts are available, but the numerical endpoint findings and inferential results are not. Without those, effect magnitude and precision cannot be assessed. Statistically, the main lesson is to distinguish a clearly stated outcome from a reported and interpretable result.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this study constrain interpretation. The registry record describes non-randomized allocation, no masking, and a single-group model. There is no concurrent comparator, so the design cannot support a controlled estimate of the intervention’s effect. The open-label feature may also influence reporting or assessment, although the record does not quantify any such influence.

The primary endpoint is named, but its numerical results are not reported. The record does not provide a mean, standard deviation, change estimate, confidence interval, p-value, or primary analysis count. It states that the primary analysis population is determined by Last Observation Carried Forward, but does not describe the amount or pattern of missing data, the number of values carried forward, or sensitivity analyses. The exact follow-up aggregation procedure is also not reported.

The study is described as a dose-titration pilot, and four dose levels are listed. The schedule and rules for titration are not reported in the registry record, so exposure by dose and the relationship between dose and outcome cannot be assessed from this information. The record names secondary outcomes but provides no numerical findings for them.

The statistical analysis plan, sample-size justification, interim analyses, multiplicity approach, and detailed outcome analysis are not reported in the registry record. The listed enrollment of 24 does not by itself establish the number included in each outcome analysis. Safety information is limited to participant counts, with no serious-event terms listed and deaths not reported. These gaps prevent a full assessment of outcome precision, missing-data effects, selective reporting, or comparative safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study Evaluating Oxybutynin in Patients With Neurogenic Overactive Bladder Associated With a Neurological Condition — NCT00224029.
• Registry record last updated 2010-04-30; status last verified 2010-04.
• Results first posted 2010-04-30.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry record describes a completed Phase 4, multi-center, open-label, dose-titration pilot study of oxybutynin transdermal systems in adults with neurogenic bladder resulting from spinal cord injury. The design is single-group and non-randomized, with no masking. Enrollment is listed as 24.

The primary outcome is the average number of catheterizations without leaking per day, measured over an 8-week timeframe. Baseline is described as a 3-day urinary diary. Doses are listed as 3.9 mg/day, 7.8 mg/day, 9.1 mg/day or 11.7 mg/day. Secondary outcomes include patch adhesion, urodynamic measurements, and urinary leakage and catheterization data.

The registry record does not report numerical primary-outcome findings or inferential analyses. It reports 0 of 24 participants affected by serious adverse events and 11 of 24 affected by other adverse events. Serious-event terms are not listed, and deaths are not reported in the registry record.